Formation of Fat in the Animal Body. 23 



fat itself, nor contains fat (Annates de C/iim. et dePhys. t. lxxi. 

 p. 65). 



M. Boussingault' s experiments correspond with universal 

 experience, and I believe are to be relied upon ; it is, there- 

 fore, the more inconceivable to me that he has placed himself 

 by the side of those who support the opposite opinion. 



A cow was fed at Bechelbrunn during eleven days upon 

 daily rations of 38 kilogrammes of potatoes, and therefore in 

 eleven days upon 418 kil. Also 3*75 kil. chopped straw; in 

 eleven days, 41*25 kil. In these eleven days she gave 54*61 

 litres of milk, which contained 2284 gram, butter. As 418 

 kil. of fresh potatoes are equal to 96*97 kil. of dry potatoes 

 (potatoes contain, according to M. Boussingault, 76*8 water 

 and 23*2 solid matter, Annates de Chim. et de Phys. 1838. 

 p. 408); further, as 1000 gram, potatoes contain only 3*05 

 gram, of soluble matter, and the straw, according to expe- 

 riments made here, contains only 0*832 per cent, of a substance 

 soluble in aether (a crystalline wax), the cow had, therefore, 

 in eleven days consumed 291 + 343 gram. = 634 gram, of 

 substance, soluble in aether. There was contained in this milk 

 however 2284 gram, of fat. 



In another case, in a trial carried on in winter, the daily 

 rations of the cow was for a long time 15 kil. of potatoes and 

 7^ kil. of hay. The quantity of milk amounted in six days 

 to 64*92 litres. These 64*92 litres of milk contained 3116 

 gram, of butter. In six days the cow consumed 90 kil. of 

 fresh potatoes, equal to 19*88 of dried; in the same time 

 45 kil. of hay were consumed. Suppose that the 19*88 kil. 

 of potatoes supplied to the cow contained 60 gram, of fat, the 

 other 3056 gram, of butter must have originated from the 

 45 kil. of hay. According to this, hay must contain nearly 

 7 per cent, of fat. This is easily ascertained by experiment. 



From hay of the best quality, in the state in which it is 

 consumed by the cows, 1 '56 per cent, of a substance soluble 

 in aether was obtained in the Giessen laboratory. Taking the 

 hay to contain 1*56 per cent, of butter, the 45 kil. of hay 

 could supply the cow with only 691 gram., there remains, 

 therefore, to discover whence the other 2365 gram, of butter 

 originated which M. Boussingault found in the milk. 



In a note which M. Dumas has appended to a communi- 

 cation of M. Romanet's (Comptes Rendus de V Acad, des 

 Sciences, 24 Oct.), the following remarks are made: — 



" Hay contains in the state in which it is consumed by the 

 cow, nearly 2 per cent, of fatty matter. We will show (MM. 

 Dumas and Payen) that the ox which is fattened and the 

 milch cow furnish a smaller quantity of fatty material than 



